More Culture:

With so many phones, tablets and computer screens in front of our faces for so many hours a day, it's fair to wonder what that's doing to our vision. Put another way: Will one more game of Candy Crush burn a hole right through my eyeballs?Curious, and a little blurry-eyed, we reached out to Lorrie Cheng, an optometrist at Temple University Hospital.

Digging into the meat of the question: What kind of damage can you do to your eyes, or your vision, by staring at screens for a long period of time?

The world is full of questions we all want answers to but are either too embarrassed, time-crunched or intimidated to actually ask. With Infrequently Asked Questions, we set out to answer those shared curiosities.

There’s a term we use, "computer vision syndrome," but it’s related to the amount of time you’re working on the computer. I want to make it clear that staring at your computer screen or your iPhone, anything like that, it doesn’t make your vision "worse." That’s the biggest concern patients feel: "I’m going to lose my vision, my prescription lens for my glasses will get worse." It’s nothing like that.

It’s the amount of time you’re staring at your computer that you might get headaches, eye strain, anything like that. A lot of times what we like to tell our patients is to give yourself frequent breaks when you know you’ll be staring at your computer for a long period of time. ... Work, schoolwork, things like that, it’s demanding on our eyes, when we’re staring at our computer screen eight hours or more a day. It’s just a matter of giving yourself enough breaks from staring at something too long. And that goes for not necessarily [just] the computer, but also reading work or any up-close work.

So does it have anything at all to do with the computer's light, or is it just the act of up-close staring?

It’s also the amount of light, the brightness ... It produces a lot of eye strain. For every 20 minutes patients are on the computer, I would like them to give themselves a 20-second break. We call that our '20-20 rule' … Unfocusing the eyes from accommodating up-close [staring] for too long.

Does the exposure to more light effect sleep?

For children [especially], using the screen on a bright screen before bedtime, that actually affects your circadian cycles, your sleep cycles. That plays a role. It might make it so that it offsets children’s sleep cycles. That’s why we would not want you to be using an iPad or something before bed. But as for decreasing vision, or something like that, you’ll get eye strain and headaches.

How long is too long to stare at a computer screen?

I want to say that every patient is a little bit different. Some patients, I don’t think they have any reason to just stop their work on a computer. But I think that 20 minutes on the computer, with 20-second breaks – if you’re doing that often you’ll be OK.

If you have eye problems already, or maybe you're a little older, does that heighten the impact of staring at the screen?

Certainly, as we get older, we start losing some of our focusing ability. I think that [comes] naturally – regardless of any computer use, I feel that when it comes to that time you might feel your vision has decreased more rapidly because of computer use. But that’s not the case. I think actually, as we get older, we lose our ability to focus up close, and because our demand [for computer use] is greater, we might feel that effectively our vision has decreased more rapidly.

How do phones play into this? Is it just as bad to stare at a phone as a computer?

It’s a lot of accommodating up close. It’s a lot of up-close work we’re doing now, and it's a lot of eye strain to stare at a small screen for a long period of time.

And the eye strain and headaches, those are the primary symptoms you’d have with computer vision syndrome?

Correct.

Anything to add? Tips?

If you’re working on a computer too long — or anything up close too long — and you have any dryness, from staring at the computer too long, because you're not blinking as often, you can use lubricating drops. And remind yourself to really give yourself a break from that computer or screen ...

Staring at your computer screen should not cause your vision to worsen, however, if you’re experiencing blurred vision and/or double vision after focusing on the computer – or “screen,” i.e. iPad or phone – that may indicate a different vision problem not caused by the use of computers, such as a binocular vision problem, and should be evaluated by your eye care doctor.

Have a question you're dying to have answered? Send an email to entertainment@phillyvoice.com, and we'll find an expert who can give you the answer you're craving.